1. Field of the Invention
This invention relates to turbocharger control systems in general and more particularly to a turbocharger control system utilized in a carburetor system including a turbocharger used with an internal combustion engine.
2. Prior art of the Invention
Turbochargers for vehicle internal combustion engines normally include a compressor impeller that compresses the air gas flow delivered to the intake manifold of the engine. In a conventional carburetor system including a turbocharger, when the air gas flow pressure delivered to the intake manifold reaches an extraordinary high value, the fuel supply will be cut off to prevent the engine from being damaged. At this time, however, a shock is given to the engine and then a speed decrease abruptly occurs, thereby having a negative influence on the engine and presenting a danger to the driver. Therefore, in a carburetor engine including a turbocharger, it is necessary to decrease smoothly the rpm's of the engine when the pressure of the air gas flow compressed by the turbocharger is extraordinarily high.
In particular, in a carburetor engine including a turbocharger positioned between a carburetor and engine cylinder chambers, when the engine is charged by the turbocharger, fuel is sucked from a venturi portion and an idle port by vacuum pressure produced by the turbocharger. Therefore, an air-fuel ratio (A/F) will be in a rich condition, resulting in deterioration of the efficiency of the fuel expense, an increase of the specific fuel consumption (FE).